A malfunctioning AC system in a hot car can be an uncomfortable experience. Not only will you overheat, but the overheating may damage components of your car. Keep reading to learn how to troubleshoot and fix AC issues.
Dash vents are not blowing air
Below are some of the most common causes of why air doesn’t flow out of your vehicle’s vents:
Faulty fuse or relay
This is one area to check that might be responsible for your dashboard air vents not working. If there is a bad ventilation fuse in your vehicle, the blower motor cannot carry out its function by blowing air through the vents.
This problem can also occur if your vehicle has a faulty relay; the relay helps to provide the current needed for the blower motor to operate. If no current stirs up the blowing motor, there will be no ventilation.
Low level of refrigerant
This is a common cause of the air conditioner in your vehicle to stop working. When the refrigerant level in your vehicle is low, you will need to notice a significant reduction in the cooling effect of the air blown into the vehicle.
This might lead to a point where the air conditioner starts blowing hot air. If there is no refrigerant in your vehicle’s cooling system, your conditioner cannot blow cool air.
Jammed air intake
Two areas allow the flow of air into your vehicle. The first area is the vents by the lower half of the windshield, and the second is the air circulated again within your vehicle’s cabin. These two areas are necessary for your vehicle’s ventilation system to function properly.
If any of these two areas are blocked by debris or any other substance, the car’s ventilation system will not be able to blow air inside your vehicle.
Faulty blower motor or resistor
The blower motor is a very important component of your vehicle’s ventilation system. This motor is a fan behind the dashboard responsible for blowing the air through the vents.
A few factors can affect the functionality of the blower motor, like electrical problems, aging, etc. However, if the blower motor cannot function, then no cool or hot air will be blown inside your vehicle when you turn on the air vents.
The blow motor functions with the aid of the blower resistor. The blower resistor helps regulate the flow of air that is blown into your vehicle as instructed by you through the air vent controls.
So, if the blower resistor in your vehicle’s ventilation system is bad, it can be why the car heater is not blowing air and affects the flow of cool air inside your vehicle.
Torn hoses or belts
The ventilation system of your vehicle is connected with various hoses that transport fluid; if there is any damage to these hoses, the ventilation system will not be able to function properly.
A torn hose can even lead to refrigerant leakage, which will reduce the effectiveness of your vehicle’s air conditioner. A broken belt can also lead to this issue.
Failed condenser or compressor
A failed condenser can prevent cool air from flowing through your vents. The condenser takes the heat of the refrigerant by changing it from its gaseous state to a liquid state.
If the condenser is damaged or blocked, it can cause your car to overheat while the AC is on due to inadequate air flowing to the air conditioner.
Potential Fixes
Note: You must be very careful when doing this; if this is not done properly, you risk more damage.
Check if the thumbwheel is set correctly
Most vehicle control doors have control to prevent you from damaging the door; this control is called a thumbwheel. The thumbwheel can be responsible for air not blowing hard out of car vents.
Clean the AC vents
Ensure you clean the dust or debris accumulated in the vents, as this can also affect the flow of air inside your vehicle.
Clean the cabin filter
Start by removing the filter. The first step to remove the cabin filter is to locate where it is installed on your vehicle. Some filters are found under the bonnet of some vehicles, while some are located under the passenger’s seat.
Once you have been able to locate the filter, gently remove the mounting screws that hold it, you can do this with the aid of a screwdriver. Then remove the filter from its housing.
You will notice specks of dust and debris on its surface if you have not cleaned the filter in a long while. Then carefully clean or replace the filter with its housing.
Replace the blower motor
A blower motor is regulated by a switch inside the vehicle or, most times, by a computer. If this motor fails, air flow through your vehicle’s vents will not flow. To know if your vehicle’s motor is faulty, you need to connect an amp meter to the blower motor’s power wire.
Next, set the amp motor to run at full speed, and when you do this, the amp meter is supposed to read between 8 to 15amps.
If the reading is lower than 8amps, your vehicle’s blower motor is faulty and should be replaced. You should take your vehicle to the mechanic’s shop for this replacement because to do this can be very technical. However, resolving this issue can fix the problem of the car heater and ac not working in your vehicle.
Clean the air intake channels
To fix this problem, locate both the air intakes of your vehicle. It is usually found at the footwell of your passenger and the windshield base. Then carefully remove the debris or substance blocking these intakes. Immediately after you are done with this, you will notice a better performance of your vehicle’s ventilation system.
Middle air vents are not working
The probable causes are listed below:
A faulty fuse or relay
This is one area to check that might be responsible for your dashboard air vents not working. If your vehicle has a bad ventilation fuse, the blower motor cannot perform its function by blowing air through the vents.
This problem can also occur if your vehicle has a faulty relay; the relay helps to provide the current needed for the blower motor to operate. If no current stirs up the blowing motor, there will be no ventilation.
Low level of refrigerant
This is a common cause for the air conditioner in your vehicle to stop working. When the refrigerant level in your vehicle is low, you will need to notice a significant reduction in the cooling effect of the air blown into the vehicle.
This might lead to a point where the air conditioner starts blowing hot air. If there is no refrigerant in your vehicle’s cooling system, your conditioner cannot blow cool air.
Jammed air intake
Two areas allow the flow of air into your vehicle. The first area is the vents by the lower half of the windshield, and the second is the air circulated again within your vehicle’s cabin. These two areas are necessary for your vehicle’s ventilation system to function properly.
If any of these two areas are blocked by debris or any other substance, the car’s ventilation system will not be able to blow air inside your vehicle.
Faulty blower motor or resistor
The blower motor is a very important component of your vehicle’s ventilation system. This motor is a fan behind the dashboard responsible for blowing the air through the vents. A few factors can affect the functionality of the blower motor, like electrical problems, aging, etc.
However, if the blower motor cannot function, then no cool or hot air will be blown inside your vehicle when you turn on the air vents.
The blow motor functions with the aid of the blower resistor. The blower resistor helps regulate the flow of air blown into your vehicle as instructed by you through the air vent controls.
So, if the blower resistor in your vehicle’s ventilation system is bad, it can be why the car heater is not blowing air and affects the flow of cool air inside your vehicle.
Torn hoses or belts
The ventilation system of your vehicle is connected to various hoses that transport fluid; if there is any damage to these hoses, the ventilation system will not be able to function properly.
A torn hose can even lead to refrigerant leakage, which will reduce the effectiveness of your vehicle’s air conditioner.
Belts (serpentine belts or fan belts), on the other hand, move the compressor and, in some vehicles, the radiator fan. If the compressor isn’t running, you won’t get cold air. If the compressor is running by the engine fan and isn’t blowing cool air over the radiator, your AC system can’t cool down efficiently.
Failed condenser or compressor
A failed condenser can prevent cool air from flowing through your vents. The condenser takes the heat of the refrigerant by changing it from its gaseous state to a liquid state.
If the condenser is damaged or blocked, it can cause your car to overheat while the AC is on due to inadequate air flowing to the air conditioner.
Some air vents not blowing air
A clogged cabin air intake or cabin filter is a likely culprit. This is a common cause, and it may not block the vents entirely; instead, the air will be limited. As a result, not only will the airflow be weaker, but the air that does come through won’t be as hot or cold as you want it, and it may smell old and stale.
Your vents not blowing air could also be a symptom of an electrical failure. If a fuse has blown or a relay no longer works, the car’s blower fan won’t get the necessary power to move air through the vents. If no air comes through the vents, it’s more likely an electrical problem than a clogged one.
There can also be physical damage to certain parts of the AC system. This is likely due to a failed blower motor, though it could also be a broken AC system hose. These require a bit more attention than a simple blockage.
Common causes for your AC not blowing air from some vents include;
Bad Electrical Relay
Relays are electrical components used to switch the current that runs through the various high-current electrical systems of your vehicle. They use a small amount of current to help control something that requires a larger current. In this case, that larger current is required by your ventilation system.
If the relay fails, your AC system can no longer draw any power from your alternator or battery, rendering it useless.
Bad Blower Motor
Based on the name, you can probably guess what a blower motor does regarding your air conditioning. This is the driving force behind the air blowing through the vents into your vehicle’s cabin. It’s essentially just a fan and subject to the kind of wear and tears you might expect from any other blowing motor.
In addition, it can get clogged up by foreign matter, burnout, or some other electrical issue preventing it from working as it should.
If your air conditioner turned on full blast, and you’re still getting a tiny bit of air blowing out of the vents but nowhere near what it should be, this is almost definitely a problem with your blower motor. In this case, the other alternative is a blockage somewhere in the ductwork.
However, the first action should be to check out the blower motor. It may be struggling, which is why it only gives you limited or no airflow.
Bad Fuse
All of the electrical systems in your vehicle rely on fuses to protect the current from overloading and shorting something out. If you blow a fuse for your ventilation system, you have severed the circuit that keeps it operating, and it won’t function again until you have a new fuse in place.
Fortunately, fuses are fairly cheap and easy to replace, so this would not be a very expensive or time-consuming repair. However, you must remember that if you have blown a fuse, something caused the fuse to blow in the first place. This could be an issue with the wiring in your ventilation system or a more serious problem.
It’s possible that even if you replace the fuse with a new one, you will suffer the same fate again quickly because whatever caused the fuse to blow in the first place will happen again.
Clogged Air Intake
Your air conditioner can’t blow any air out of the vents if it can’t get any air into the system in the first place. This is because your car has a fresh air intake that draws air in from the outside and another that recirculates air inside the vehicle. The air conditioner relies on both of these to function properly.
Suppose the intake is clogged. The AC’s inside air intake can easily be clogged by fallen leaves and other debris. In that case, your air conditioner will not be able to blow any air out because there’s simply nothing blowing through your ventilation system.
Bad Hoses
Any one of several hoses throughout your ventilation system could break down on you, which would cause it to no longer function properly. If these hoses come loose, get clogged, or wear out, you won’t have the airflow you expect from your air conditioner when you turn it on.
Bad Switch
This is a less common cause for your air conditioner not blowing air out of the vents, but it’s possible that the switch on your dashboard itself is not working.
If the dial or the button you’re using isn’t properly connected because something has broken inside, then your air conditioner can’t get the signal that you want it to work, and that’s why no air is blowing.
But, again, it’s not a problem with the air conditioner itself. It’s just that your air conditioner is not getting the proper signal from the controls that it needs to turn on.
Bad Air Filter
You have an air filter under the hood of your car for your engine, but there’s also a second air filter in your vehicle’s cabin. If your cabin air filter is severely blocked with dust and debris, you will drastically limit the air flow from your air conditioning unit.
It could get so bad that no air can circulate as well. So it’s always a good idea to check your air filters anytime you go in for routine maintenance, like changing your oil filter, for instance.
Driver side vent not working
There are two common causes of a temperature difference include;
Low Refrigerant
Automotive air conditioners which use 134A usually hold a small amount of refrigerant compared to older automobiles that use R12. Today, car and truck air conditioners are much more efficient than their older counterparts. The fact that 134A systems use less freon means that a leak can more quickly affect the Air Conditioning system’s performance.
Due to the design of dual AC systems, low refrigerant is the leading cause of drastic temperature differences from one side of the dash to the other. Even experienced car mechanics may be surprised to learn that as little as 4 to 8 ounces undercharged 134A can make such a huge difference.
The temperature from the left vent to the right vent can vary from 10 to 20 degrees. So the easiest thing to try is to top off the system or remove all freon and recharge the unit with the factory-specified amount. In most cases, after the proper charge of Freon is in the car, the temperature will blow equally as cold as it should on both sides.
Door Issue
Dual zones supplying different temperatures from vents on either side of the dash are achieved using small doors within the HVAC housing. By controlling the doors, the air temperature on the left and right can be adjusted to the desired comfort level.
Often, the motor (or actuator) that controls the door for either side can fail, or the door can break and prevent the temp from being adjusted.
AC only blows through floor vents
Below are the main causes of airflow to feet only;
Air Leak
If the air conditioner only blows to the floor vents, regardless of whether the car is accelerating hard, the leak could be somewhere between the switch valve and the engine.
If the leak is somewhere between the switch valve and the engine, the vacuum actuators will never get the right amount of vacuum to work properly and default to blowing only on the floor vents.
You will still need a vacuum gauge and a smoke machine to verify. This will allow you to ensure that there are no other leaks you need to patch since your system is losing a lot of vacuum.
Again, without these two tools, you have no choice but to bring your car to a mechanic or a service center to test the rubber tubes, locate the leaks, and patch them.
Faulty Vacuum System
When the engine produces less vacuum at high RPMs, the check valve shuts off the connection to the engine to prevent losing the vacuum to the engine. This is when the vacuum stored in the reservoir takes over the duty of providing a vacuum to the air conditioning system to control the air doors.
The vacuum coming from the engine is more stable than the one coming from the reservoir. Thus, when the check valve isolates the engine at high RPMs, you will expose a leak in the system because the reservoir cannot provide the same constant vacuum as the engine. This will result in insufficient vacuum to trigger the vacuum actuator valve.
The vacuum actuator valve is a switching mechanism for cars that use the vacuum from the engine to control where the air conditioner will blow the cold air. The vacuum actuator closes and opens the air door to redirect cool air where you want them to be.
The vacuum actuator will remain at its default position if there is an insufficient vacuum. In some cars, this is to open the vents to your feet, while some default to defrost and combine both.
How To Fix A Leaking Vacuum Control Air Vent System
To find where the leak is, you will need a vacuum gauge and a smoke machine.
- The vacuum gauge will allow you to test the rubber tubes by isolating them one by one.
- The vacuum gauge will drop once you connect it to a leaking rubber tube.
Once you identify which rubber tube leaks, connect that tube to a smoke machine. Smoke will escape the rubber tube leak, which will tell you where the leak is. You can patch the leak with a vacuum tube patch or trim off the leak and connect the two parts of the tube with a vacuum connector.
However, without a vacuum gauge and a smoke machine, your only option is to bring your car to a certified mechanic to locate and patch the leak for you.
Alternatively, you can bring your car to a mechanic to replace the part for you.
Some cars don’t use a vacuum control air vent system and instead use a manual air vent control. This system changes the direction of the cold air when you change the position of the control knob.
However, this system can fail when there is insufficient grease, and the telescoping air distribution control shaft that transfers the movement on the knob to the air doors breaks or comes loose.
Once the telescoping air distribution control shaft breaks, you will no longer be able to change the position of the air doors. If the last position is to blow cold air only on the floor vents, then it will stay that way until you replace the broken part.
When replacing any part on your car, it is important to get the exact part number to ensure that you get the correct replacement with the correct measurements. Using the wrong part can damage other parts of your car and cause a bigger problem.
You will need to remove many parts of the dashboard to replace the telescoping air distribution control shaft. You can get the service manual for your particular car model to learn how to properly remove the parts of your dashboard to replace the problem part.
AC is only running at one speed
The odds are good that the fan switch may be at fault. Still, a more likely reason is that a blower motor resistor that controls the voltage going to the blower has packed it in, resulting in only one speed remaining operable — usually, the highest speed, which you may not always need depending on the temp of the outside air.
When a blower resistor fails, the highest fan speed is usually the only one that still works because it essentially bypasses the resistor and receives the maximum voltage. When the resistor works, it reduces the voltage to lower fan speeds, so the fan runs slower.
Blower resistors are small parts that can become corrupted or burnt out, and a new one often costs less than $50. Because they’re usually under the dashboard on the passenger’s side or behind the glove box of a vehicle, near the blower motor, they can be hard to reach if and when they need to be replaced.
Though having only one fan speed usually indicates a bad blower resistor, a diligent mechanic at a repair shop will test the resistor, fan switch, and connections to the motor. To ensure nothing else is wrong before they start replacing parts. If none of the fan speeds work, then checking the fuse or fuses for the heating, vent, and air-conditioning systems is a logical first step.
Weak airflow from AC vents in the car
There are several common reasons for weak airflow in AC systems, some of which can be fixed at home and others that require the expertise of professional technicians.
The main causes of weak airflow include;
Mold and mildew growth
The presence of moisture inside air conditioner units can be the ideal environment for mold and mildew to thrive. Unfortunately, this can reduce airflow by blocking the fins at your heat exchangers behind the dashboard, producing unpleasant odors in the cabin, and putting the health of your passengers at risk.
Cleaning your evaporator using a good quality coil cleaner will normally eradicate mold and mildew. You should also use an anti-bacterial cleaner to remove harmful germs from the system. Running the defrost mode regularly will help to keep your air conditioner dry and prevent further issues.
Loose hose or seal
Another common cause of weak airflow is that the blower hose has come loose, meaning that air is not passing through the evaporator into the cabin. One of the multiple seals in the system could also be a problem, which must remain tightly closed to ensure air can pass through. A professional technician should only ever repair or replace hoses and seals.
Blocked cabin filters
The cabin filter also called a pollen filter, is typically located before your blower motor and acts as a filtration system between the outside air and your car’s cabin. Any pollens, dirt, leaves, or general road debris gets stopped at the cabin filter to ensure your passengers only breathe clean air. Cabin filters do not last forever and should be changed every 20,000 km.
Faulty fan
The ventilation fan is responsible for blowing air over the evaporator unit, which is cooled by the refrigerant before entering the cabin. If the airflow is weak or non-existent, the fan may be damaged and must be replaced for normal operation to resume.
Closed vents
Make sure the vent controls on the dashboard are open, and the vent is pointing outward. Depending on your vehicle’s style, the vent control can get hung up, so sometimes, closing and reopening them with the thumb wheel is all needed.
Clogged air filter
In most cases, weak airflow is caused by a clogged-up cabin air filter. Over time, this filter catches all dirt and debris, which can build up and slow or stop airflow. It’s typically located under the dash on the passenger side or inside the glove box and should be cleaned or replaced regularly.
Solution:
Instead of changing the cabin air filter, it is often recommended first to clean the filter. This can be done, for example, with a vacuum cleaner or a compressed air system, removing at least a large part of the visible dirt particles. Unfortunately, this procedure does not allow you to get into the deeper layers of the filter. Therefore, the filter performance will not increase significantly even after cleaning. As a rule, there is no avoiding a change if the filter is dirty.
Dirty evaporator
A dirty evaporator can significantly reduce your vehicle’s AC airflow and cooling performance. The cabin air filter captures most of the dirt or other airborne particles, but some particles escape and can get lodged in the evaporator. Over time, these particles build up on the fins and block the airflow through the evaporator coil, causing poor airflow from AC vents and degraded cooling performance.
Symptoms of a dirty evaporator
The two most prominent symptoms of a clogged-up evaporator are: the airflow from the AC vents is choppy and not smooth, and the inside of the vehicle is developing a bad moldy smell.
Cleaning the evaporator is not a simple task. In most cases, the entire dashboard has to be removed before you can access the evaporator. Therefore, it is recommended to do this in a workshop.
Clogged fan
This one is a bit of a long shot, but it could be the fan has become clogged up with debris. You’d be shocked how much junk can find its way into the duct system of a car. Everything from leaves to rodent nests seems to find their way down in to the fan area. Make sure it is clean with nothing to impede the flow of air.
Faulty Cable or motor
All vehicles give you the option to have your ac come out up top or on your feet using a series of blend doors that direct the air to the proper set of vents. Small motors on most modern cars control these doors but, in some cases, can also be moved using cables. Either way, if the cable or motor isn’t working properly, it won’t completely open and close the blend doors and cause an air leak and lower airflow.
Blocked Intake
There are two intakes, one for fresh air located at the base of the windshield and one for recirculated air that can be found in the passenger side footwell. If either of these intakes is obstructed, it can severely hamper the flow of air.
Keeping your ac flowing at max performance is important to keeping cool. If your vehicle’s climate control is suffering from low airflow air conditioning, check out these areas for blockages.
Frozen evaporator
Evaporator coil freezing up due to insufficient refrigerant in the AC system can cause weak airflow from the AC vents. In this case, the vents should blow air normally when you first turn on the AC after starting the vehicle, but the airflow gradually decreases as frost or ice forms on the evaporator coil. The refrigerant level can get low due to a leak or if the AC has not been recharged for a long time.
Refrigerant leak
A low refrigerant level in your vehicle does not necessarily mean a leak. Ideally, the refrigerant should never leak in a properly sealed AC system. Still, most car AC systems leak a small amount of refrigerant over time due to minor imperfections and will need recharging every few years.
Suppose you don’t service the AC system in your vehicle for a long time. In that case, the refrigerant level will eventually get so low that the system loses its cooling capacity. The airflow may also be restricted due to ice formation on the evaporator coil. Just have it refilled, and you can drive with pleasant temperatures again. If the refrigerant level goes down again quickly, there is probably a leak.
Refrigerant leak causes
A refrigerant leak can be caused by leaking O-ring seals, a leaking condenser or evaporator core, or a cracked hose. The leak can be diagnosed by injecting a small amount of fluorescent dye into the AC system. The leaking component will shine under UV light when the refrigerant leaks again.
How to recharge AC refrigerant
There are two ports in the air conditioning system of modern cars. One is labeled H for high-pressure, and the other is L for low-pressure. You can recharge your AC through the low-pressure port with a do-it-yourself AC recharge kit.
- Open the hood of your vehicle.
- Check which type of refrigerant your vehicle uses. This information is stored under the hood and in the owner’s manual.
- Start the engine.
- Turn on the AC and set it to the coldest setting, maximum fan speed.
- Remove the cap from the low-pressure service port labeled L, and connect the AC recharge kit.
Note: If the ports are not labeled, try connecting the recharge kit to unlabeled ports on the AC hoses. The recharge kit will only properly connect to the low-pressure port and will not fit the high-pressure port.
Shake the canister briefly and release the refrigerant into the system until the recommended pressure has been achieved.
Warning: Wear gloves and safety glasses before recharging the AC to avoid accidental exposure to harmful chemicals in the refrigerant. It is also cryogenic and can cause severe frostbite when it comes in contact with the skin.
Dirty blower motor
The blower motor is the central component of the air conditioning system, responsible for blowing hot or cold air through the AC vents. Although most of the dirt and other particles in the air are filtered by the cabin air filter, some particles escape and can cling to the fins of the blower cage. As a result, over time, dust can accumulate on the fins and reduce the airflow, reducing cooling performance.
If too much dirt is caked in the blower fins, it can throw off the balance of the spinning cage and cause it to wobble. This strains the motor, further reduces airflow and cooling performance, and may cause unusual noises from behind the dashboard.
To clean the blower motor, remove the blower motor, typically located under the passenger side dashboard, and inspect the condition of the cage. If found dirty, clean it using a brush.
Sluggish blower motor
Suppose the blower motor is not spinning fast enough due to an internal defect or a fault in the resistor/control module. In that case, the airflow from the AC vents will be weaker, and the cooling performance will be degraded due to reduced airflow.
When a blower motor goes bad, it usually makes unusual noises when operating, and the passengers may feel reduced airflow from the AC vents. However, keep in mind that reduced airflow doesn’t always indicate a problem with the blower motor, as it can also happen due to a clogged cabin air filter, dirty evaporator, or a bad-mode door actuator. So, all of them must be inspected when diagnosing poor airflow.
Faulty mode door actuator
The mode door actuator is part of the AC system which controls the airflow through different vents (front, floor, or defrost) based on user settings. If this actuator develops a fault or goes out of calibration, the airflow may get divided between different vents resulting in reduced airflow from your desired vents.
For example, if you have set the airflow from the front vents only, but the mode door actuator doesn’t fully divert the airflow to the front vents, the air is leaking from the floor or defrost vents. Put your hand over the defrost vents on the dashboard to check if it leaks any air. If the air is leaking, replacing this actuator should resolve the issue.
Car AC air direction control is not working
Below are some reasons why your AC direction controls are not working;
Faulty Control Module
The terminology for this component can vary based on your car’s make and model, but the control module is the physical unit inside the cabin. This component contains the buttons, dials, and screens you use to adjust the cabin temperature. In most cases, it also includes the electronic hardware necessary to control your heating and cooling equipment.
A faulty control module can produce a vast array of different symptoms. Since you’re poking and prodding at the controls regularly, mechanical issues are not uncommon. These can take the form of damaged screens, broken buttons, loose dials, and any number of other defects. Unfortunately, the replacement of the whole module is often the only solution.
Electronics failures within the module may have more unpredictable results. For example, in some cases, your climate control may stop responding to your temperature settings or otherwise behave erratically. The system’s odd, seemingly random behavior typically points to an electronic issue.
Failed Sensors
If your control module is working correctly, then a failed sensor may be to blame. The most straightforward climate control systems still require two sensors: an ambient temperature sensor outside the car and an interior cabin temperature sensor. Together, these two sensors determine the strength and temperature of the air coming from your vents.
More sophisticated systems on higher-end vehicles may also use additional sensors. For example, most modern cars have multiple temperature sensors located within the cabin to help provide more even heating and cooling. Your car might even have sensors to compensate for the strength of sunlight entering through your windows or to check the body temperature of vehicle occupants.
With so many sensors, a faulty reading from one or more can drastically impact the efficiency of your vehicle’s heating and cooling systems. Fortunately, bad sensors often trigger a fault code in the car’s computer.
Bad Blend Motors
The complexity of an automatic climate control system doesn’t end with control modules and sensors. Most systems use specialized motors to control the exact temperature of the air entering the cabin. These electric motors allow the climate control system to blend the amount of warm or cold air entering the cabin to maintain your desired temperature.
A broken blend motor may stop functioning entirely, or it may no longer be able to report its position to the control module. Since the control system must be aware of the motor’s position to control air temperature properly, either situation can lead to unusual behavior. A failing motor may also produce noticeable noises, even if it is not yet impacting the system’s operation.
Unless the problem with your climate control system is as simple as a blown a fuse, you likely won’t be able to diagnose it yourself. As vehicle HVAC systems become more and more complex, proper diagnosis and repair move beyond the ability of shade tree mechanics.
Fan running but no air coming out of vents
There could be many reasons for it, but here are the top 5 reasons ;
Leaky Seals or Hoses
Coolants and refrigerants in the heating/cooling systems within sealed hoses are prone to leakage due to a lack of maintenance. This is the most common cause of such failure.
Finding the leakage without taking a full view from beneath the car is difficult, but you can check it during regular servicing. While checking your gas charge is also a good time for such a diagnosis.
Note: Ask your service provider to check for leaks during your scheduled car service. And, don’t skip it because there are many good reasons why you should not skip car service.
Faulty Thermostat
There’s a slim chance your car has a manufacturing fault in the thermostat. The usual reason for such a fault is fluctuating cabin temperatures. However, if your car is fitted with a manual cooling/heating control, there could be a problem with the switch, compressor clutch, sensor, or even pressure cut-out.
Faulty Compressor
This reason is rather conspicuous. If you hear loud, weird noises while you switch the AC on, it indicates a faulty AC compressor. Besides, it could also indicate a problem with the pressure of the refrigerant.
Also, chances are that you have been using the wrong kind of compressor lubricant. So make sure that the noise isn’t coming from the engine. If it is, get your car checked by a mechanic as soon as possible.
Electronic Issue
Automatic and manual cars with advanced electronic features often suffer from this problem. The more complex your car, the higher the chances for electronic faults. When more electronic features are added to your cooling/heating system, it increases the chances of things going out of order.
It may increase the ease of use and comfort, but it also increases the scope of repairs. Electronic faults could be one of the major reasons why heating or AC stops working.
Mildew and Bacteria
Loss of cooling or heat could also be because of bacteria build-up. There is a possibility that mold, bacteria, or mildew may have accumulated on the evaporator coils. The clear symptom of this problem is the weird smell in the cabin.
It is important to cater to the problems immediately when you start noticing the symptoms. In cases where no symptoms manifest, it can be a bummer. To avoid this, ensure you do the suggested checks during service.
Troubleshooting steps if your AC isn’t working
Check the gas pipe temperature
You can check if there are abnormal signs quickly by touching the gas pipe. Found warm in the high-pressure line, and cool in the low-pressure line is okay. Manufacturers of high-pressure tubes have a smaller diameter than low-pressure tubes.
If the temperature between the two tubes does not differ much, your air conditioning may be a problem.
Check the compressed air system
The second one is due to the crankshaft connecting the engine to the compressed air, resulting in loss of power, and the compressor can’t compress the refrigerant to the required pressure. But, again, you can open the bonnet and check the compressed air system.
Check the wind speed of the AC
Besides, there are also reasons such as the cold soiled dirt that causes the wind to be blocked and the heat dissipation, resulting in the reduced cooling effect. You can check whether the wind speed is strong or weak. If the high voltage and low-pressure wires are normal, it may be necessary to clean the chillers.
To measure the cooling effect, keep the engine at 1,500 rpm, and air conditioning at the highest level. After 5 minutes, you can measure the cabin’s temperature and the wind blowing out of the cooler. Of course, you should check the entire air conditioning system if the temperature is high.
Air coming out of the wrong vents in the car
Different underlying issues may make your car’s air conditioning system only blow cold air on one side. Some of the possible reasons for that concern are:
Wrong Interior Climate Controls
Some cars have climate controls that give users separate temperature regulators for each vent. Generally also called the dual-climate or dual-zone climate control feature, cars like certain Chevy Malibu and Ford F-150 models allow drivers and passengers to fine-tune temperature levels for the driver and passenger’s preferences.
Check your car’s owner’s manual to verify if your vehicle has a dual-climate cooling and heating system. If so, read the instructions to control this feature since the steps to use it often depend on specific models.
Bad Blend Door Actuator
A blend temperature door actuator is a motor assembly that helps control the vehicle’s climate control features. For example, cold air may only blow through one of the vents if this assembly breaks or malfunctions.
Some of the signs that your blend door actuator is at fault are:
- Clicking, knocking, or other strange sounds when using your car’s AC
- Inconsistent air conditioner temperature and/or airflow
- Incorrect temperature produced
Low Coolant Charge
Inconsistent performance from the car’s cooling system may mean that your vehicle needs a coolant recharge. If the engine doesn’t have sufficient refrigerant, the cooling features might have difficulty disseminating the correct temperatures for the entire vehicle.
Aside from only blowing cold air to one vent, low coolant can also promote risks for other serious problems. For instance, driving with insufficient refrigerant can increase the engine’s temperature, which may lead to overheating.
Broken Vent Door
Normal wear-and-tear may cause a car’s air vent door to break. A common sign that you need to replace this component is when it can’t maintain its position and orientation. If this is the case, the vent door may remain closed, preventing cold air from passing through it.
How to Replace A Blend Door Actuator
Before proceeding with this replacement project, ensure that the blend door actuator you’re about to install is compatible with your vehicle. After purchasing the correct assembly, continue this task by following these steps:
Items Needed
- Wrenches
- Panel removal tool
- Replacement blend door actuator
Step-By-Step Guide
- Remove the panel on either the driver or passenger side of the cabin. Again, remember to base your decision for this step on the location of the faulty part.
- Unscrew and take out the metal shielding.
- Detach the old blend door actuator by taking out its connected wires carefully.
- Install the new blend door actuator while paying attention to its position and orientation.
- Secure the assembly and reinstall the removed parts.
- Turn on the air conditioner to test if the problem persists.
How to unclog dashboard air vents
Follow these steps to unclog your air vents;
Items needed
- Spray bottle
- Warm water
- Liquid soap
- Scrub brush
- Compressed air
- Vacuum cleaner
- Dust mask
Cleaning Steps
- Ensure that your engine is turned off and no power goes to your air duct system.
- The vents on your car should be able to pop out, but you might need to use a screwdriver to remove them.
- Be careful not to break or damage them when taking them out. If you find this too difficult, you can still get a quality clean by leaving them in.
- Mix some liquid soap with warm water into your spray bottle and shake it up.
- Spray some of the solution onto your vents and the air duct walls if you can reach them.
- Be sure to use a detailing brush to help break up any build-ups without scratching the plastic.
- Get as deep as you can into all the ducts of your car. Don’t forget the ones near your windshield or any of the ones underneath your dashboard by your feet.
- The dirt, dust, and grime should be loosened up now so that you’ll be able to use your vacuum to get most of it pretty easily.
- Try to get into your ducts as deeply as possible to suck up anything that might be trapped there.
- Using a vacuum with strong suction will help provide you with a thorough cleaning of your vents.
- A household vacuum may be enough, but you might need to enlist a heavy-duty vacuum for the best results.
- Your vacuum most likely got the vast majority of dust, but using compressed air can help you make sure.
- Take the time to go the extra mile and get deeper into your air duct system by spraying compressed air into your vents.
- You will want to use a face mask just in case a lot of dust is trapped in your ducts.
- Spray the compressed air liberally into each of your vents to give it a final clearing.
- Run your vacuum over your vents just to be safe, and then use it to pick up anything that might have come up during step five.
- If you removed your air vents earlier, replace them in their original location.
How to control where the AC blows air from in your car
The best way to do this is by using the automatic mode. Automatic air-conditioning employs a range of sensors to ensure constant thermal comfort, whether the driver is alone or the whole family is in the car, travelling in sweltering weather to get to the seaside or in the freezing winter to get to the ski slopes.
Press the Auto button and set the temperature, ideally around 22 °C. Even if the AC sign is lit up, this does not mean that the air-conditioning delivers all it can. Modern systems regulate the operation of the compressor to reflect current conditions. In doing so, they draw on a solar sensor that monitors the intensity and direction of the sun’s rays.
One of the key advantages of automatic air-conditioning is safety. For example, if the windows start fogging and you are using manual air-conditioning, you need to increase the fan speed to ensure a good road view. But this increases the noise level emitted by the fan and the airflow. An automatic system prevents fogging before it even starts, and increasing the fan speed is the last resort.
Climate control takes air conditioning and does away with the guessing game of temperature change. Just as its name suggests, it allows you to accurately dictate the exact temperature of the air entering the cabin, even to half-degree increments. It is effectively air-conditioning, but with a brain.
This is accomplished using a feedback loop or closed loop control system. This means that the output from the system is translated into some form of information and sent back as feedback to the input controller so adjustments can be made. So if you set your climate control at 17 degrees centigrade, the climate control will form a feedback loop to keep the cabin at that temperature.
More advanced systems use sunlight detectors on the dashboard to predetermine the amount of heat entering the car through solar radiation. If large amounts of sunlight are detected, the controller will increase A/C in preparation, reducing any form of lag within the heat-exchanging process.
Air Only Blows Through Defrost Vents
Defrosting is a vital function that can keep your vehicle from freezing and icing up in cold winters. Moreover, not only is a part of the ventilation system merely working hard to do its job, but the defroster plays an important role when it can affect the smoothness of the temperature control system and the safety and health of the vehicle, as well as the driver.
Below are some reasons why your AC is stuck on defrost;
Blown Fuse In The Ventilation System
The sting of witnessing air only blows through defrost vents in the car can also be triggered by a blown fuse. The part protects the entire ventilation system from dangerous sudden overvoltages (electrical surges). When this unpleasant phenomenon occurs due to a short circuit, electricity will not be able to reach the blower motor. Thereby, the ventilation system may stop working.
You need to pay attention to three types of fuses if encountering the above situation. They are ventilation fuses, fan fuses, and the air conditioner’s compressor magnetic clutch. In general, fuses protect the windings that link the entire electrical circuit or limit the severe explosion cases in the system of your vehicle.
You need to pay attention to monitoring and checking the fuses in the car regularly. If they still blow even after you have just replaced them before, take your vehicle to the nearest repair shop for a comprehensive consultation and review.
Bad Relay
A relay controls the current required for ventilation. The relay must supply current to the blower motor for it to work. If this does not happen, the ventilation system will be restricted, causing air to be forced through only defrost vents.
Due to the continuous opening and closing acts, the relay is tolerant to wear and tear. And this is also one of the reasons why the blower cannot work properly to ensure the ventilation system in the car does not encounter any obstacles. Another sign of a faulty relay is if you feel warm or hot when you touch it, it indicates that the relay has absorbed too much heat due to the breakdown.
Check and replace the relay periodically if you don’t want its problems to add more complications to the entire ventilation system and air quality every time you enter your vehicle.
Bad Mode Door Actuator
The first cause of AC only blows through defrost vents issue is a faulty door actuator. The function of the mode door actuator is to control the vents to ensure that air will be blown out properly according to the custom settings.
Many modern door actuator systems have gradually been developed based on automation. As you notice, even modern systems that integrate multiple types of high-performance technologies will wear and break down over time, let alone the manual ones. The actuator is also always in a vulnerable stage as it is often exposed to air from different raw air sources.
It is a device equipped with gears made of plastic that can easily be broken and slide apart during operation. Not only that, the door actuator can face many problems and operate incorrectly due to overloading, incorrect or confusing wiring, poor quality of incoming air, and even poor mounting.
One of the most noticeable signs that show the mode actuator’s problem is when you turn on the air conditioner, the vent slot in the front will make a click sound, and that is when the air only blows through defrosting vents issue happen.
And the next noticeable thing is that you have to find a way to deal with this problem. When the mode door has a hard time working properly, you must unplug it immediately and rotate inside with your fingers.
If your rotation feels smooth and there seem no difficulties running, you can be free with it. However, remember to clean up your car mode door actuator from time to time to ensure it will operate smoothly and effectively during a season with extreme weather if, unfortunately, encountered.
Obstructed Air Intake
Normally, air will enter the car in two main ways: the vents above the dashboard and the duct where the air is recirculated in the car. However, if both of the above air blow lines are blocked or obstructed by obstacles, the vehicle will face an issue of AC stuck on defrost, where the air will be concentrated in one vent while unable to escape.
Clogged air intakes are mostly caused by obstacles falling into the air vents when you are traveling on the road, such as tree nuts, fallen leaves, long sharp sticks, or branches of bird nests. All of these direct factors cause blocked vents that you need to deal with immediately to avoid long-term hard-to-fix consequences.
The filthy vent system will affect the air quality and temperature every time you travel. And no matter how fresh that destination may sound, the polluted car air still brings you a not-so-good experience.
To solve this problem, you should clean and possibly replace the air filters without spending too much time analyzing why the air only blows through defrost vents.
You can completely pump clean air to filter out the pollutants that cause health problems. Also, any homemade solutions you can think of for cleaning air intake are highly recommended to save money instead of going to the repair shop, as long as it doesn’t damage or break the system.
Try to clean the air intake at least once a week with specialized cleaning solutions at supermarkets. Although they are just small, simple actions, they will be effective in the long run.
Broken Motor Blower
The blower motor is one of the most vital parts of the car ventilation process. The function of this part is to blow air through the vent. It can also check the air blowing when combined with a blower motor resistor. With such irreplaceable functions, a damaged blower motor will cause quite a few serious problems for your car.
A vehicle operating with a damaged fan motor can not exhaust air through the vents, resulting in no airflow to regulate and balance the air inside the cabin. The most common problems with the blower motor are corrosion and tearing.
As it fails, you can easily spot the problem thanks to the loud hum when you start the air conditioning system, or you will hear an unusual vibration.
If you have to travel for a long time and your car operates longer than usual, you may smell a burning smell coming from the air vents due to overload and overheating. And gradually, starting from a seemingly small part, each component of your engine will be damaged if they often face problems of air restrictions, the most noticeable causes of rust and overheating.
The best way to take care of a damaged blower motor is to identify the causes and deal with the problems. If you don’t want any opponents of the car to suffer from overheating due to air restriction, pay close attention and take good care of the ducts.
You should also be careful of rust problems, limiting dirt from entering your blower motor. Finally, promptly fix any leaks in the blower motor if you notice strange smells or noises, and change the air filter periodically.
Faulty Blower Resistor
The blower resistor will blow cool or warm air through the vents when you turn on the air conditioner/heater and adjust the car air fan to operate at multiple speeds to suit your needs. When the car AC is stuck on defrost vents, your wind resistor may be faulty and needs intermediate repair.
Thermal overload or overheating is the leading cause of this problem. So, to give the blower resistor total control of airflow rate and strengthen the cabin air, have it replaced at a professional repair shop.
Damaged Blend Door Actuator
The function of a blend door actuator is to regulate and control the temperature in the car by permitting or preventing air from passing through the heater core. Unfortunately, this part is composed of gears made of plastic, which are quite fragile and unstable.
Being made from non-rigid materials will create more opportunities for the blend door actuator to expose exclusively to damaged and broken conditions. Not only that, but this part is also prone to work erratically or even stop functioning when the electric motor is in a state of exhaust caused by excessive and prolonged operations.
Keep an eye on the temperature in your car every time you turn on the air conditioner. Suppose you feel the temperature gradually becomes erratic or not effectively cooling and warm as you have customized the system.
In that case, your blend door actuator will likely have problems that need immediate repair. However, before the actuator is completely damaged and cannot be repaired with regular cleaning and maintenance methods, you can easily hear the small ticking noises coming from the dash.
Given the problems considered quite serious with this type of actuator, temporarily trying to fix it is not a good idea. However, you can always replace the broken one with a brand new one with just a few basic disassembly and tools.
If you are not confident in your mechanic skills, find a reputable repair facility to ensure the system will come back to work smoothly within the fastest time.
Car AC maintenance tips
Getting in a stuffy, secretive, and smelly car is something no one wants. So remember to identify the cause and deal with it appropriately to avoid wasting valuable time on fruitless efforts.
Take good care of your vehicle’s ventilation system, air conditioner, and all the components contributing to a great fresh ride. You might be surprised at what a small act of maintenance can do to a car built up with a thousand pieces.
Run your A/C weekly on defrost mode
You should run your air conditioning weekly for 10 minutes on defrost mode on the coolest setting and at the maximum fan speed. This helps maintain gas pressure, keeps your compressor running well, cleanses moisture, and prevents mildew.
This includes running your air conditioning in the winter, which helps remove humidity and works well to defog the windshield.
Don’t pre-cool your car
Your car’s air conditioning operates at maximum efficiency when you’re driving. Don’t pre-cool your car. On extra hot days, put the fan on high once you start driving and open only the backseat windows for 10 to 20 seconds to force out the hot air.
Set A/C to the coldest setting
Your car’s air conditioning is most efficient when set to the lowest temperature and adjusting the fan for comfort. Most air conditioning systems cool the air to 3-4 C. A higher temperature forces the system to reheat the air, burning more fuel.
Keep your car clean
Dirt and bacteria can negatively impact your car’s air conditioning system. Keep dirt and debris at bay by regularly cleaning, dusting, and vacuuming. Car aircon cleaning is crucial for the system’s optimal functioning and efficient working.
Like any other component with a build-up during the functioning period, an aircon system must be cleaned and scrubbed regularly.
A dirty filter is inefficient and might lead to bigger and more expensive issues when left untreated. Moreover, blocking airflow would demand extra work from the aircon system, which would lead to more stress on the engine, thereby affecting the overall working and fuel economy of the vehicle.
The interior of the aircon system is susceptible to bacteria build-up, which requires regular cleaning, dusting, and even vacuuming by professionals. This also helps to prevent the accumulation of dust and debris, keeping the airflow uninterrupted and the cabin fresh and odor-free.
When you go in for a regular service check, ensure that your mechanic takes a look at the air filter/pollen filter and cleans or replaces it, as need be. The good idea is to get it cleaned before summer.
Another very uncommon but essential car aircon cleaning tip is to keep the radiator clean. Since the AC condenser is situated in front of the radiator in the car engine, any overheating may be transferred to the condenser, disrupting the entire working mechanism. A clean and topped-up radiator would not overheat and prevent the entire mishap.
The Recirculation Hack
Many car owners advocate the use of the recirculation button for the efficient working of the aircon system. However, if you use it without paying attention to how it works and how you can use the button effectively, it won’t help your cause much.
Recirculation can lead to misting up of the windows. If you encounter this, open the windows a little to allow the mist to clean up. Another word of caution – while using the recirculation system, you should pay enough attention to the rear-seat passengers.
While the aircon system pulls the air from the front and cools it, the air at the back can be warm, stale, and, therefore, unhealthy. If you have the latest car model, the latest technology allows you to use the ‘auto’ mode, which self-regulates the circulation process, keeping the inside of the cabin cool.
The idea is not to push the recirculation button right when you switch on the car and sit inside. Instead, it makes the air-con system circulate the existing hot air in the cabin, thereby beating its main purpose.
The aircon maintenance tips say that you should turn off the recirculation button for a while, allowing cold air to enter the cabin from the compressor. Then, once the optimal temperature is reached, turn on the recirculation mechanism. It will help it to work with what is already in the cabin, but with much fresher and cooler air.
Check refrigerant level
The air blown out of the AC keeps your car cool, and this air is cooled with the help of a refrigerant. Therefore, checking the refrigerant level is essential and a must item in the car AC maintenance checklist.
Bring mechanics’ notice to check the optimal refrigerant level, as the regular service schedule does not include this.
Regular servicing of the AC is a must
Machines need regular servicing and proper maintenance to run smoothly. Your ac also needs adequate servicing. Ensure you take your car to the mechanic regularly and get servicing for your ac on regular periods. This will also increase the longevity of the machine.
Nowadays, a specialised air conditioning car service is provided at many garages. Car air conditioner repair is also necessary in case of any severe damage.
Replace cabin air filter regularly
The cabin air filter traps dust particles and pollutants from outside your car. However, low maintenance of cabin filters may result in clogging with dust and contaminants, and it will also start retaining moisture. This dust retention can turn your cabin filter into a breeding ground for germs and bacteria.
The air filter of your air conditioner should be changed every year.
Use the Air conditioning system in the correct way
For proper air conditioner maintenance, learn to use the air conditioning system in a good way. Care can’t guarantee a long life of your ac if you do not operate it smartly.
Wherever you enter the car, lower down the glass and turn on the fan blower with a fresh air dial setting to allow the fresh air in your car. This will release the hot and warm air outside and regulate the inside temperature.
After a few minutes, shut the windows and let the AC regulate the cabin’s temperature. Once the weather becomes optimal, turn the dial from fresh air to recirculating air and reduce the fan speed.
Shut down everything
This might not look relevant to many, but it is a very crucial step. Turning off everything in order is essential. For example, the aircon should be turned off first, followed by the ignition. If you switch off the engine without first turning off the aircon, the fan keeps running and leads to the build-up of moss and bacteria.
You can let the fan move after switching off the ac to ensure evaporation. This will save your car from turning into a breeding ground for bacteria.
A switched-off and rested air-conditioner will clear the evaporator and the nearby components, avoid any growth of moss and bacteria, and keep the air fresh, good-smelling, and healthy. It will also help your aircon last longer.
Parking in shade
Park your car in the shade to avoid overheating the cabin. Avoid parking in direct sunlight. It will not only make the cabin humid and your steering wheel a part of hell but might also damage the upholstery, leather seats, and even the dashboard.
Find a shady spot to park your car, especially while parking for the entire day. It would be best if the sun is behind you. This will help keep the steering wheel and the front seats much cooler and more comfortable.
Moreover, a very hot cabin requires extra pressure on the car A/c to decrease the temperature. Additionally, overheating of the car can damage the engine. Parking the car in the shade will prevent it from excessive heating and help maintain the car’s optimal temperature.
Ventilate your car
Besides other car AC tips, remember proper ventilation is necessary for you and your car’s health. Intake and exhaust of the air will maintain an optimal temperature inside the vehicle.
Recharge the AC system
The importance of recharge in the air-conditioning system is often overlooked even by the most seasoned driver. The aircon system might not demand the kind of attention that other parts do, but it does work a lot to provide the cabin with cold air.
The work involves refrigerant circulation through the various components to cool down the air before it is distributed through the vents into the cabin.
Aircon maintenance becomes essential since the refrigerant demands regular top-ups to maintain the efficient working of the system. It is said that an average air-conditioner should be topped up/replaced with a refrigerant every two years or so.
If you notice a dip in the air-conditioner’s performance or haven’t recharged it, it would be a good idea to take it to a service center. Furthermore, many aircon systems are also a victim of refrigerant leakage of refrigerant. So make sure you have it professionally checked if there is a constant need for recharge and poor functioning.
Set the air jets at the correct angle
When you keep the air jets pointed to the face, the airflow is not equally distributed. Therefore, it leads to no significant difference in the cabin air.
However, aiming the vents upwards or towards the roof assists in dispersing the cool air more evenly. Thereby making the whole process more effective and efficient.
Run your AC weekly
Run the air-running to optimize the compressor’s functioning and keep the gas pressure at an optimum level. Set it to the coolest setting along with the fan on the fastest speed, and let it work.
Do this once every week, and you will notice fresher air, better cooling, and a drop-down in the mechanical issues. It also helps to avoid any build-up of moisture or moss.